<template>
  <div id="Application">
      <!-- 游戏区域 -->
      <div class="container">
          <!-- 底部挡板 -->
          <div class="board" :style="{left: boardX + 'px'}"></div>
          <!-- 弹球 -->
          <div class="ball" :style="{left: ballX+'px', top: ballY+'px'}"></div>
          <!-- 游戏结束提示 -->
          <h1 v-if="fail" style="text-align: center;">游戏失败</h1>
      </div>
  </div>
</template>

<script>
import { defineComponent } from 'vue';

export default defineComponent({
  data() {
      return {
          // 控制挡板位置
          boardX: 0,
          // 控制弹球位置
          ballX: 0,
          ballY: 0,
          // 控制弹球移动速度
          rateX: 0.1,
          rateY: 0.1,
          // 控制结束游戏提示的展示
          fail: false
      };
  },
  mounted() {
      // 添加键盘事件
      this.enterKeyup();
      // 随机弹球的运动速度和方向
      this.rateX = (Math.random() * 0.5 + 0.1);
      this.rateY = (Math.random() * 0.5 + 0.1);
      // 开启计数器，控制弹球移动
      this.timer = setInterval(() => {
          // 到达右侧边缘进行反弹
          if (this.ballX + this.rateX >= 440 - 30) {
              this.rateX *= -1;
          }
          // 到达左侧边缘进行反弹
          if (this.ballX + this.rateX <= 0) {
              this.rateX *= -1;
          }
          // 到达上侧边缘进行反弹
          if (this.ballY + this.rateY <= 0) {
              this.rateY *= -1;
          }
          this.ballX += this.rateX;
          this.ballY += this.rateY;
          // 失败判定
          if (this.ballY >= 440 - 30 - 10) {
              // 挡板接住了弹球，进行反弹
              if (this.boardX <= this.ballX + 30 && this.boardX + 80 >= this.ballX) {
                  this.rateY *= -1;
              } else {
                  // 没有接住弹球，游戏结束
                  clearInterval(this.timer);
                  this.fail = true;
              }
          }
      }, 2);
  },
  methods: {
      // 控制挡板移动
      keydown(event) {
          if (event.key == "ArrowLeft") {
              if (this.boardX > 10) {
                  this.boardX -= 20;
              }
          } else if (event.key == "ArrowRight") {
              if (this.boardX < 440 - 80) {
                  this.boardX += 20;
              }
          }
      },
      enterKeyup() {
          document.addEventListener("keydown", this.keydown);
      }
  }
});
</script>

<style>
body {
  margin: 0;
  padding: 0;
}
.container {
  position: relative;
  margin: 0 auto;
  width: 440px;
  height: 440px;
  background-color: blanchedalmond;
}
.ball {
  position: absolute;
  width: 30px;
  height: 30px;
  left: 0px;
  top: 0px;
  background-color: orange;
  border-radius: 30px;
}
.board {
  position: absolute;
  left: 0;
  bottom: 0;
  height: 10px;
  width: 80px;
  border-radius: 5px;
  background-color: red;
}
</style>
